The U.S. EPA has sent a proposed position on whether GHGs are currently "subject to regulation" to the White House Office of Management and Budget for review. The proposal is expected to either affirm or reverse former EPA Adminstrator Jackson's position that GHGs are not subject to regulation because, despite the fact that EPA has the authority to restrict their emission, EPA has not done so to date. When a pollutant is subject to regulation under the Clean Air Act, new and modified stationary sources must implement the best available control technology to limit the emission of the pollutant. Thus, if EPA states that GHGs are not currently "subject to regulation," environmentalists will have greater difficulty in their efforts to block the construction of new and modified coal-fired power plants for the failure to include GHG emission limiting technology. The significance of EPA's decision on whether GHGs are currently subject to regulation is somewhat diminished in light of the fact that EPA will soon issue regulations restricting GHG emissions from vehicles, at which point there is very little doubt that GHGs would be subject to regulation.